A conventional lead-acid cell comprises, in a battery housing-forming vessel for a liquid electrolyte, especially sulfuric acid, a positive electrode whose active mass consists predominantly of lead dioxide in a charged state and a negative electrode whose active mass consists predominantly of lead in the charged state.
The literature makes it clear, as does experience, that such lead-acid cells, also termed lead accumulators, should not be operated at temperatures above about 50.degree. C except for brief intervals. At higher temperatures, the power output and the useful (recycling) life of the cell both diminish.
In practice it has been found, with such conventional cells, that the electrode tend to deteriorate at elevated temperatures by the separation of active material therefrom and that there is an increased oxidation of the separators and loss of water from the battery by increased vaporization. The latter results in an increased concentration of the acid of the electrolyte.
This effect is so well known that high-energy, large lead-acid accumulators of the type used to drive motor buses, for example, are provided with expensive weight-increasing and energy-consuming cooling systems to abstract or dissipate the Joule heat developed in the battery during operation thereof.